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OPA365: OPA365 Input Impedance

Part Number: OPA365

What is the specification for the input impedance at the OPA365 input terminals? In the datasheet, it only mentions it has a "high input impedance" but there is no value listed in its specifications.

  • Hi Roland,

    the input bias current is such extremely low, that the input impedance is entirely dominated by the input capacitance. Even at low frequencies the input current flowing caused by the input capacitance is decades higher than the static input bias current.

    Also, if you have a look at figure 6 of datasheet, you can see that there's almost no variation of input bias current with input voltage at Vcm=Vcc/2. And it's hard to estimate whether you can apply the Ohm's law, at all. In such a situation in datasheet only the input capacitance and the input bias current is given but no input resistance.

  • Hi Roland,

    The OPA365 device has CMOS inputs with > 1Tohms or 10^12 ohm input impedance. That's the reason why the input bias current is very low on the order of +/-10pF max.

    Best Regards,